1. Field of the Invention
The present invention relates to an adjustable head for a wrench. In particular, the present invention relates to a wrench including a handle and a head that can be pivotally adjusted to and retained in a desired angular position relative to the handle.
2. Description of the Related Art
FIG. 1 of the drawings illustrates a conventional wrench including a handle 2 and a head 1 that can be pivotally adjusted to a desired angular position relative to the handle 2. FIG. 2 is a top view of the head 1, and FIG. 3 is a side view of the head 1.
The head 1 includes a pair of lugs 12 on a side thereof, with teeth 121 being defined along an arcuate outer surface section of the respective lug 12. A pin 14 is extended through aligned pin holes 122 in the lugs 12 and a pin hole 22 in an engaging portion 21 formed on an end of the handle 2, thereby pivotally connecting the lugs 12 of the head 1 to the engaging portion 21 of the handle 2.
In this wrench; formation of the teeth 121 along an entire arcuate outer surface section of the respective lug 12 of the head 10 causes a reduction in the thickness; namely, the distance from a periphery delimiting the hole 122 of the respective lug 12 to the dedendum circle of the teeth 121 is “L”. As illustrated in FIG. 1, the respective lug 12 is subjected to a torque at sections 122a and 122b when the wrench is turned clockwise for driving a fastener. Cracks 13 are apt to be generated in the torque-bearing section 122b when the handle 2 is turned clockwise. The torque-bearing section 122b is damaged when the torque applied to the wrench is relatively large. The device for retaining the head 1 in a desired angular position relative to the handle 2 sacrifices the torque-bearing capacity of the wrench.